The invention relates to a method and apparatus for dispensing or metering one or several constituents of flowable substances, especially of printing inks. Storage means contain a plurality of storage containers for different constituents. The storage containers each comprise outlet valve means. At least one metering station is included. The metering station receives the storage containers conveyed to it. Actuating means at the metering station actuates the outlet valve means. A conveying means conveys the storage containers to the at least one metering station.
A metering apparatus is shown in EP 0 391 286 A1. Here, a plurality of canisters are arranged on a rotary table. In order to meter and add individual constituents to a mixed product, the table is moved into a respective position where an individual canister is rotated into a dispensing and metering station. The actuating means in the metering station act on the canister so that a defined quantity of the constituent in the station, is introduced into a mixing or collecting container. Each of the canisters inserted into the rotary table is provided with integrated outlet valve means which can be controlled by actuating means associated with the metering station. In an apparatus of this type, the number of canisters for individual constituents is limited by an acceptable size of the rotary table with a given size of the individual canisters.
The canisters each comprise an outlet valve which, in the position as inserted into the rotary table, points downwards. In particular, the outlet valve means are in the form of a ball cock. At their open end opposite the outlet valve means, the canisters each have a displacement piston which is loaded and displaced by setting means in the metering station while the outlet valve is opened. Underneath the displacement piston, an air cushion is present to prevent direct contact of the flowable medium, e.g. especially printing ink, with the displacement piston.
In the rotary table, within the canister receiving means which are positioned on one diameter designed for being introduced into the metering station, a second canister receiving ring is provided on a second inner diameter to insert reserve canisters in a reversed position in which they cannot be actuated. This measure simplifies the operation of manually exchanging emptied canisters against reserve canisters.
To increase the number of addable constituents as a function of the number of canisters in the rotary table, a storage bin is provided. The storage bin is not functionally connected to the rotary table. Canisters can be manually inserted into the receiving means of the rotary table. However, the canisters have to be exchanged against canisters being present in the receiving means.
The control process is based on certain individual canisters associated with certain receiving positions in the rotary table. This is due to a home position orientating itself entirely on the position of the rotary table. A flag for a zero position is arranged directly at the rotary table. Further flags are arranged at the rotary table to measure the travel to the individual canisters.
The apparatus of the above type is thus designed for a limited number of constituents and for small quantities of constituents to be mixed.
An apparatus of a similar type is illustrated in EP 0 461 371 B1. Here, a plurality of storage containers each contain one dye substance. The containers are arranged in a predetermined number so as to be firmly associated with one another. The containers are on a rotary plate or on a slide which is movable in two directions. The storage containers are spray bottles with a sleeve containing the dye and with a gas bubble thereabove. The gas bubble may be under a pre-pressure, but the pre-pressure may also be generated entirely by the elasticity of the elastic sleeve. Pressure compensation takes place between the air bubble thereabove and the environment. Each of the storage containers is provided with integrated outlet valve means. In a metering station into which one of the storage containers is guided, the outlet valve means are opened by setting means. A collecting container inserted into the metering station loads a weighing device which controls the setting means for the outlet valve means.
In the case of this apparatus, the storage containers include a code containing information on the contents of the respective storage container. The code is scanned mechanically. To increase the number of the individual storage containers, two concentric circles of receiving means are provided in a rotary plate. Also, to increase the number of storage containers, individual discs are allowed to rotate within a rotary plate. The discs each have a plurality of receiving means for storage containers. Nevertheless, the total number of storage containers is limited by the size of the rotary plate or by the size of the slide. In addition, because of the design of the storage containers, their size can be assumed to be relatively small. The purpose of this apparatus is to produce mixtures of hair dyes.
U.S. Pat. No. 4,867,258 discloses an apparatus to produce mixtures of pourable powdery or granular substances. Here, a plurality of mixing containers is arranged together in a magazine. The mixing containers can be transported individually to a metering station. A plurality of powder storage containers is arranged in a different magazine. The powder storage containers, for the purpose of adding a constituent, are also transported individually to a metering station. The transport means includes one single linear conveying slide and a transversely movable magazine for the individual storage containers. Each storage container is moved in this linear way into the metering station. Each container has to be returned from there into its position in the magazine before the magazine moves and before the next storage container is transported by the same means and in the same way into the metering station and returned from there. The magazine contains only a small number of storage containers.
The above assemblies are not suitable for metering printing inks in ink factories or printing works. In such applications, the number of constituents required and the absolute quantity of inks is so large that a total supply of several tons in weight always has to be available. The consumption of the individual constituents varies, so that it must be possible to exchange, or add to, individual storage containers in a problem-free way without interrupting the operation of the at least one metering station. This objective cannot be achieved with devices with rotary plates or slides whose purpose it is to allow the use of the complete number of constituents dispensed under undisturbed and uninterrupted operational conditions. Therefore, for such applications, it has so far been common practice to use systems with fixedly installed storage containers and with fixed pipelines leading from each individual storage container to a metering station. Each of the individual pipelines has its own pumping means and its own valve means which are freely controllable. The amount of equipment required is considerable and involves high purchase and maintenance costs. The individual pipelines contain large quantities of ink which constitute a non-usable dead volume. Inside the pipelines, the ink is subject to early ageing. Exchanging inks involves high losses and considerable cleaning efforts.